fairfax county typical deck details county, virginia typical deck details based on the 2012 virginia...

Fairfax County, Virginia

Typical Deck Details

Based on the 2012 Virginia Residential Code

The design details in this document apply to residential, single-level decks only. Construction cannot deviate from the details herein unless prior approval is obtained by the county. A copy of this document must be on the job site and available during each required inspection.

Version: 2012.6, 1/31/2018 Fairfax County, Virginia - Typical Deck Details of 24

Fairfax County, Virginia Typical Deck Details

CONTENTS guard

joists

post

rim joist

footing

guard postattachment

beam

ledger boardattachment toexisting house

existing housefloor construction

ledger boardfasteners

decking

post-to-beamconnection

joist-to-beamconnection

knee-bracing

blocking

Section 1 General Notes .........................................3 Design Considerations .............................................3 Material Specifications ............................................3

Section 2 Deck Surface ..........................................4 Decking ....................................................................4 Safety Glazing ..........................................................5 Electrical ..................................................................5

Section 3 Joists ........................................................6 Joist Size ..................................................................6 Joist Framing at Projections .....................................8 Joist Hangers ............................................................8 Joist-to-Beam Connection ........................................8

Section 4 Beams ......................................................9 Beam Size ..............................................................10 Beam Assembly .....................................................10

Section 5 Footings & Posts ..................................11 Footing Size ...........................................................11

Post-to-Footing Connection ................................... 12 Post Size & Maximum Height ............................... 11 Beam-to-Post Connection ...................................... 12

Section 6 Ledger Attachment ............................. 13 General Requirements ........................................... 13 Ledger Board Fasteners ......................................... 15

Section 7 Lateral Support ................................... 17 Bracing Methods ................................................... 17 Bracing-to-Framing Connection ............................ 19

Section 8 Guards .................................................. 19 Guard Construction ............................................... 19 Guard Post Connections ........................................ 20

Section 9 Stairs ..................................................... 21 Stair Geometry ....................................................... 21 Stair Landing ......................................................... 21 Stair Construction .................................................. 21

Section 10 Complete My Deck .......................... 24


1 General Notes

These typical deck details are provided to ensure design and construction of decks in Fairfax County is consistent and code compliant. Prior to designing your deck, read this publication thoroughly and pay close attention to each applicable detail. Once you have selected the size of your deck, use the joist and beam span tables to determine their size, spacing, span lengths and overhang dimensions. Use the remaining details to guide you in determining the other design elements of your deck. Ensure you record your deck design on Page 24.

If you have questions, please contact the county at 703-631-5101, TTY 711 or via email at [email protected]. Information regarding permit application, zoning setbacks and inspection requirements can be found from the website.

Fairfax County is committed to a policy of nondiscrimination and will provide this document in alternative formats and languages upon request. Please contact the county at 703-222-0801, TTY 711 or [email protected]. Allow seven working days for preparation of material.

DESIGN CONSIDERATIONS

1. These details are based on the prescriptive requirements of the 2012 Virginia Residential Code, industry best-practices and applicable referenced standards such as the National Design Specification for Wood Construction.

2. Framing members in these details are designed for a 40 PSF live load, 10 PSF dead load, normal loading duration, wet service conditions and deflections of ℓ/360 for main spans and ℓ/180 for overhangs with a 220-pound point load.

3. The use of these details to design and construct multi-level decks is prohibited.

4. Deviation from these details require approval by county staff prior to construction.

5. Decks constructed in accordance with these details are not approved for privacy screens, planters, built-in seating or hot tubs.

6. Decks must be designed to ensure rain and melting ice and snow flow away from the existing house.

7. Publication “DCA6” from the American Wood Council can also be used to obtain a permit in Fairfax County. Go to awc.org to download.

MATERIAL SPECIFICATIONS

1. Lumber shall be preservative-treated, southern pine, grade #2 or better. Lumber not native to North America, such as Ipe, may be used as decking only; its use in guards is prohibited.

2. Lumber in contact with the ground shall be rated as “ground-contact.” Not all treated lumber is rated for ground contact.

3. Concrete in footings shall have a minimum compressive strength of 3,000 PSI.

4. Nails shall be threaded, ring-shanked or annular grooved. A ⅛-inch pilot hole shall be used at toe-nailing locations.

5. Carriage-bolts may be substituted where through-bolts are specified provided carriage-bolt washers (with square holes) are installed at the bolt head.

6. Fasteners shall be hot-dipped galvanized, stainless steel or approved for use with preservative-treated lumber.

mailto:[email protected]

https://www.fairfaxcounty.gov/landdevelopment/sites/landdevelopment/files/assets/documents/pdf/publications/decks.pdf

mailto:[email protected]

http://www.awc.org/Publications/DCA/DCA6/DCA6-09.pdf


7. Hardware and mechanical connectors, e.g., joist hangers or post anchors, shall be stainless steel or galvanized with 1.85 ounces of zinc per square foot (G-185 coating). Look for product lines such as “Zmax,” “Triple Zinc” or “Gold Coat.”

8. Flashing at ledger board connections (see Page 13) shall be copper (with copper nails only), stainless steel, UV resistant plastic or galvanized steel with a G-185 coating.

9. Plastic composites are materials composed of bound wood and plastic fibers. Permissible as noted in this document, plastic composites must bear a label indicating its compliance with ASTM D 7032. Plastic composite’s label and installation instructions must be available to the inspector.

10. When using plastic composites, exercise caution as some members do not have the same capacity as their wood equivalents.

11. PVC decking and guards are permitted provided they have a valid evaluation report from an accredited listing agency such as the International Code Council – Evaluation Service. Installation shall be in conformance with the report and the manufacturer's instructions which must be available to the inspector. For a list of approved products, go to fairfaxcounty.gov and search on “structural plastics.”

12. The use of other materials and products, other than those permitted herein, shall be approved by the county prior to installation.

2 Deck SurfaceDECKING

• Decking shall be per TABLE 1 and placed perpendicularly or at an angle up to 45 degrees to the joists. • Wood decking shall be attached per FIGURE 1. If installed wet, place decking with no gap so after drying

a ⅛-inch gap is created. • The use of hidden fasteners and similar attachment devices is prohibited. • Each decking member shall bear on a minimum of three joists or blocking between joists. • Placement and attachment of plastic composites shall be per manufacturer’s instructions.

(2)8d nails or (2)#8screws at each joist

1 8" typical gap

2x4, 2x6 or "five-quarter" board

after drying

FIGURE 1: TYPICAL DECKING

TABLE 1: DECKING REQUIREMENTS AND MAXIMUM JOIST SPACING

Material Type and Maximum Joist Spacing (inches) Nominal Size Angular Perpendicular

Wood “five-quarter” board 12 16 Wood 2x4 or 2x6 16 24

Plastic composites, PVC per manufacturer per manufacturer

http://www.fairfaxcounty.gov/


SAFETY GLAZING

To reduce injury due to an accidental impact, safety glazing in window glass is required when the existing house wall encloses any portion of the deck surface or acts as a barrier to stairs, landings and areas at the top and bottom of the stairs.

Windows adjacent a deck surface. As shown in FIGURE 2, single panes of glass meeting all the requirements listed below must be safety-glazed.

• Glass area is greater than 9 square feet, • The bottom edge of the pane is less than 18 inches above the walking surface of the deck, and • The top edge of the pane is greater than 36 inches above the walking surface of the deck.

In the absence of safety glazing, a horizontal rail across the window must be installed. The rail must meet the requirements of a stair handrail per Page 23.

Windows adjacent stairways and landings. Single panes, partially or wholly located in the hatched area shown in FIGURE 2, must be safety-glazed. In the absence of safety glazing, a stair guard per Page 22 or handrail per Page 23, must be constructed to separate the window from the stairway.

36"

60"

36"

walkingsurfaceof deck

lowerwalkingsurface

<18"

single panearea > 9 sf

>36"

safety glazingrequired

ADJACENT STAIRS/LANDING

ADJACENT DECK SURFACE

safety glazingrequired

no safety glazingrequired

FIGURE 2: SAFETY GLAZING REQUIREMENTS

ELECTRICAL

Outlets. Decks shall have a minimum of one electrical outlet along the perimeter of the deck and within 6.5 feet of the floor.

Stair lighting. Each stairway section shall have a light source that illuminates all stairs and landings. Lights shall be operated from interior switches, motion detectors or timed switches. Low voltage lighting at each stair tread is permissible.


3 Joists• Joists are repetitively placed framing members spaced at 12, 16 or 24 inches on center which are

supported at each end by a beam or ledger board. • Single span decks are framed with joists that have one span between supports (not including overhang)

as shown in FIGURES 3 and 4. Multi-span decks have joists with more than one span which bear on multiple beam as shown in FIGURES 5 and 6.

• At the house connection, joists bear on the attached ledger board. Joists on a free-standing deck do not connect to the house; instead bearing is provided by an additional beam located at or near the house wall as shown in FIGURE 7.

JOIST SIZE

• Joist span length is measured from the ledger board to the centerline of the supporting beam or between the centerlines of the supporting beams at each end.

• Joists are permitted to overhang past a dropped beam; joist span length does not include overhangs. • The joists’ design is based on spacing, size and span length. Use TABLE 2 to determine joist size and

the corresponding maximum allowable overhang. Note: the overhang dimension shall never exceed one-fourth of the actual joist span.

• Provide full-depth 2x blocking between overhanging joists above beam locations. Exception: blocking may be omitted if the overhang is less than or equal to 2 feet.

• Where blocking between joists is required, attach blocking using joist hangers at each end or by toe-nailing blocking to joists at each end, top and bottom with 10d nails.

• Attach a continuous rim joist or blocking at the joist ends as shown in FIGURES 3, 5 and 7. Attach a rim joist to the end of each joist with (3)10d nails or (3)#10 by 3-inch wood screws.

• When choosing 2x6 joists, the corresponding ledger board must be a 2x8 minimum. See Page 13 for more information.

• Guards cannot be attached to decks framed with 2x6 joists. See Page 20 for more information. TABLE 2: MAXIMUM JOIST SPAN LENGTH

Joist Spacing (inches on center) Joist Size Allowable

Span Allowable Overhang1

12 2x6 9'-11" 1'-3" 12 2x8 13'-1" 2'-1" 12 2x10 16'-2" 3'-4" 12 2x12 18'-0" 4'-6" 16 2x6 9'-0" 1'-4" 16 2x8 11'-10" 2'-3" 16 2x10 14'-0" 3'-6" 16 2x12 16'-6" 4'-2" 24 2x6 7'-7" 1'-6" 24 2x8 9'-8" 2'-5" 24 2x10 11'-5" 2'-10" 24 2x12 13'-6" 3'-4"

1 Overhang dimension shall not exceed one-fourth of the actual joist span.


post

joist hanger

joistdropped outsidebeam

joist span

continuousrim joist

optional overhang

blocking (betweenoverhanging joists only)

ledgerboard

FIGURE 3: SINGLE SPAN DECK - JOISTS ATTACHED AT HOUSE WITH DROPPED BEAM

joist hanger

joist

joist hanger

post ledgerboard

joist span

flushoutsidebeam

FIGURE 4: SINGLE SPAN DECK - JOISTS ATTACHED AT HOUSE WITH FLUSH BEAM

post

joist hanger

droppedinsidebeam

joist-1 span

continuous rim joist

optional overhang

blocking (betweenoverhanging joists only)

post

dropped outsidebeam

joist-2 span

ledgerboard

joist-overlap1

joist-21 joist-11

1 One continuous joist is permitted to span over the top of the inside dropped beam with no overlap.

FIGURE 5: MULTI-SPAN DECK - JOISTS WITH DROPPED BEAMS

post

joist hanger

joist-1flush insidebeam

joist-1 span

post

flushoutsidebeam

joist-2 span

joist-2 ledgerboard

FIGURE 6: MULTI-SPAN DECK - JOISTS WITH FLUSH BEAMS

droppedoutsidebeam1

droppedoutsidebeam1

joist spanoptional overhang

2x blocking between joistsor continuous rim joist

continuousrim joist blocking (between overhanging joists only)

optional overhang

joist2

post2post2

1 Flush beams are permitted with freestanding decks when joists do not overhang. 2 Align joists to be located at post locations in order to accommodate lateral bracing per FIGURE 29.

FIGURE 7: JOISTS WITH FREESTANDING DECKS


FRAMING AT PROJECTIONS

Additional framing and ledger board fasteners per Section 6 on Page 15 are required at projections such as chimneys or bay windows as shown in FIGURE 8. Each ply of the header shall be equal to the deck joist size. Joist hangers shall meet the requirements below.

PLAN VIEW SECTION

decking overhang 6" max.

3' m

ax.

three-ply1 trimmerjoist, each side

three-ply1 trimmer joist

two ledgerboard fasteners

6' maximum

chimney orbay window

ledgerboard

ledgerboard

two-ply header

chimneyor baywindow

1 May be reduce to two-ply trimmer joist if joist spacing equals 24 inches on center or joist span is less than or equal to 8.5 feet.

FIGURE 8: FRAMING AT CHIMNEY OR BAY WINDOW

JOIST HANGERS

• Joist hanger depth, d, as shown in FIGURE 9, shall be greater than or equal to 60 percent of the joist depth.

• The manufactured width of the joist hanger shall accommodate the number of plies being carried. • Do not bend hanger flanges to accommodate field conditions. • Joist hangers shall be fastened to the ledger board or flush beam using its manufacturer’s recommended

screws. All other fasteners are permitted to be nails. • Use joist hangers with inside flanges when clearances to the edge of the beam or ledger board dictate. • Clip angles or brackets used to support framing members in lieu of joist hangers are prohibited.

joist hanger with inside flanges

d

fasteners to ledger board or flushbeam shall be hanger manufacturer'srecommendation screws

FIGURE 9: JOIST HANGERS

JOIST-TO-BEAM CONNECTION

• Each joist shall be attached to the beam in accordance with FIGURE 10. • Mechanical connectors or hurricane clips shall have a minimum capacity of 100 pounds in both uplift

and lateral directions. Installation shall be per manufacturer’s instructions. • As shown in FIGURE 10, multi-span joists are permitted to span continuously over a dropped interior

beam with one mechanical connector or overlap with a mechanical connector at each joist.


overhanging or multi-span continuous joists

overlapped joists bearingat inside beams

mechanical connector orhurricane clip each sideof joist-overlap

joists shall span toopposite edge of beam top of flush beam and joists

shall be at same elevation

mechanical connector orhurricane clip, typical as shown

(3)10d nails at joist-overlap

FIGURE 10: JOIST-TO-BEAM CONNECTION

4 Beams• Beams are assembled, multi-ply framing members which span between supporting posts. Multi-span

decks have more than one beam; spacing between beams is dependent on the allowable span lengths of the supported joists.

• Inside beams have joists bearing from each side. Outside beams have joists, with or without an overhang, bearing from one side.

• Dropped beams have joists bearing above; flush beams have joists with hangers bearing on its sides; see FIGURES 3 through 7 and FIGURE 11.

• Multi-span decks are permitted to mix flush and dropped beams.

BEAM SIZE

• Beam size is based on its influence width and longest span length per TABLE 3. Beam influence width, as shown in FIGURE 12, is based on supported joists’ span lengths and overhang dimensions.

• Beam span length, as shown in FIGURE 11, is measured between the centerlines of two adjacent posts and does not include the beam overhangs.

• Beams may overhang past the center of the post up to one-fourth of the actual beam span. • Flush beams shall have a depth greater than or equal to the deepest joist.

beam spanoptional

overhang

DROPPED BEAM

beam span

FLUSH BEAM

beam

post post

beambeam splice atinterior postlocations only

joists

joists

beam spanoptional

overhangoptional

overhangoptional

overhang

FIGURE 11: BEAM TYPES


influence width1

2 joist-1span

12 joist-2span

joist-1 span joist-2 span

influence width1

2 joist span overhang

joist span

OUTSIDE DROPPED BEAM

12 joist span

joist span

OUTSIDE FLUSH BEAM

INSIDE DROPPED BEAM

influence width

influence width1

2 joist-1span

12 joist-2span

joist-1 span joist-2 span

INSIDE FLUSH BEAM

influence width1

2 joist spanoverhang

joist span

BEAM AT FREE-STANDING DECK

FIGURE 12: BEAM INFLUENCE WIDTH

TABLE 3: MINIMUM BEAM SIZE 1

Beam Influence Width (ft)

Longest Beam Span Length (feet), less than or equal to:

less than or equal to: 6 8 10 12 14 16 18

2 (2)2x6 (2)2x6 (2)2x8, (3)2x6 (2)2x8 (2)2x10, (3)2x8 (2)2x12 (3)2x10 3 (2)2x6 (2)2x6 (2)2x8 (2)2x10, (3)2x8 (2)2x12, (3)2x10 (3)2x10 (3)2x12 4 (2)2x6 (2)2x8, (3)2x6 (2)2x10, (3)2x8 (2)2x12, (3)2x10 (3)2x10 (3)2x12 NA 5 (2)2x6 (2)2x8, (3)2x6 (2)2x12, (3)2x8 (3)2x10 (3)2x12 NA NA 6 (2)2x8, (3)2x6 (2)2x10, (3)2x8 (2)2x12, (3)2x10 (3)2x12 NA NA NA 7 (2)2x8, (3)2x6 (2)2x10, (3)2x8 (3)2x10 (3)2x12 NA NA NA 8 (2)2x8, (3)2x6 (2)2x12, (3)2x8 (3)2x12 NA NA NA NA 9 (2)2x10, (3)2x6 (2)2x12, (3)2x10 (3)2x12 NA NA NA NA

10 (2)2x10, (3)2x8 (3)2x10 (3)2x12 NA NA NA NA 11 (2)2x10, (3)2x8 (3)2x10 NA NA NA NA NA 12 (2)2x10, (3)2x8 (3)2x10 NA NA NA NA NA 13 (2)2x12, (3)2x8 (3)2x12 NA NA NA NA NA 14 (2)2x12, (3)2x8 (3)2x12 NA NA NA NA NA 15 (2)2x12, (3)2x8 (3)2x12 NA NA NA NA NA 16 (2)2x12, (3)2x10 (3)2x12 NA NA NA NA NA 17 (2)2x12, (3)2x10 (3)2x12 NA NA NA NA NA 18 (3)2x10 NA NA NA NA NA NA

1 Design conditions which fall within the shaded cells are prohibited.

BEAM ASSEMBLY

• The plies of the beam shall be fastened in accordance with FIGURE 13. • The distance from the centerline of the fastener to the top or bottom edge of the beam shall be ½-inch

minimum. • The distance from the centerline of the fastener to the ends of the beam shall be 1-inch minimum. • Beam plies are permitted to have splices. However, splices shall be located at inside posts connections

as shown in FIGURE 11.


10d nails or #10 x 3" woodscrews, staggered in 2 rows

2 fasteners at eachend and splices

16" typical For 3-ply beams,attach eachoutside ply toinside as shown

1" min.

12" min. top

and bottom

FIGURE 13: BEAM PLY FASTENING

5 Footings & PostsFOOTING SIZE

Footing size is found by using TABLE 4 to obtain the footing type based on the beam influence width and the longest beam span length and TABLE 5 to determine the minimum footing dimensions.

• Footing sizes shall be consistent for each beam and designed for its maximum span. • Footings shall bear on solid ground 24 inches below grade; footings shall be deeper if solid ground is not

found. Bearing conditions must be verified by county inspectors prior to placement of concrete. • When the edge of a deck footing is closer than 5 feet to an existing exterior house wall, the footing must

bear at the same elevation as the existing house footings as shown in FIGURE 14. • Do not construct footings over utility lines or service pipe. Call Miss Utility at 811 before you dig.

TABLE 4: FOOTING TYPE AND MAXIMUM POST HEIGHT 1

Beam Influence Width (ft)

Longest Beam Span Length (feet), less than or equal to:

less than or 6 6 8 8 10 10 12 12 14 14 16 16 18 18 equal to: Footing

Type Max.

Post Ht. Footing

Type Max.

Post Ht. Footing

Type Max.

Post Ht. Footing

Type Max.

Post Ht. Footing

Type Max.

Post Ht. Footing

Type Max.

Post Ht. Footing

Type Max.

Post Ht.

2 A 14 A 14 A 14 A 14 A 14 B 14 B 14 3 A 14 A 14 B 14 B 14 B 14 B 14 C 14 4 A 14 B 14 B 14 B 14 C 14 D 14 5 B 14 B 14 C 14 D 14 E 14 6 B 14 B 14 D 14 E 14 7 B 14 C 14 E 14 E 13 8 B 14 C 14 E 13 9 C 14 D 14 E 12

10 D 14 E 13 F 11 11 D 14 E 13 12 E 14 F 12 13 E 14 F 11 14 E 13 F 10 15 F 12 G 9 16 F 12 H 9 17 G 11 H 9 18 G 11

1 Design conditions which fall within the shaded cells are prohibited.


when less than 5',footings must beat same elevation

FIGURE 14: FOOTINGS ADJACENT EXISTING HOUSE

TABLE 5: FOOTING SIZE

Type Sides of Square

(inches)

Diameter of Round (inches)

Thickness (inches)

A 12 14 6 B 14 16 6 C 16 18 6 D 18 20 6 E 20 22 8 F 22 24 8 G 24 26 9 H 26 28 10

POST-TO-FOOTING CONNECTION

• Post attachment requirements shall be in accordance with FIGURE 15. • Post anchors shall have a 1-inch minimum base. • Posts shall be centered on the footing.

frost depth

24" m

inim

um

pre-manufactured postbase with cast-in-placepost anchor

12" diameterconcrete stem

1" minimumpost base

thic

knes

spe

r tab

le1

grade

size per table1 size per table1 size per table1

1 See TABLE 5 for footing dimensions.

FIGURE 15: FOOTINGS

POST SIZE & MAXIMUM HEIGHT

• Post size shall be 6x6 with a maximum height based on the corresponding beam influence width and longest beam span length in accordance with TABLE 4. Posts with a height less than or equal to 2.5 feet are permitted to be 4x4.

• Post height is measured from the top of the footing to the underside of the beam. • Cut ends of posts shall be field treated with a wood preservative containing copper naphthenate which

can be found in the paint department of most hardware or home center stores.

BEAM-TO-POST CONNECTION

• Beams shall be attached to 6x6 posts using one of the methods shown in FIGURE 16 or 17. Beams shall be attached to 4x4 posts using the method shown in FIGURE 17.

• 4x4 posts are prohibited from supporting three-ply beams. • Beams shall not be attached to the sides of an unnotched post as shown in FIGURE 18. • Pre-manufactured post caps shall be specifically designed for two- or three-ply beams and the post size

used. Attachment shall be per manufacturer's instructions.


beam mustbear on notch

212" min.

(2)12" diameterthrough-bolts

notch post for flushbeam bearing

SECTION

two-plybeam only

TYPICAL POST POST AT BEAM SPLICE

>212" min.

>34"

>2"

>34"

<5"

beamsplice

FIGURE 16: NOTCHED 6x6 POST-TO-BEAM CONNECTION

pre-manufacturedpost cap

two- or three-ply beam

post

FIGURE 17: POST CAP CONNECTION

FIGURE 18: PROHIBITED CONNECTION

6 Ledger Board AttachmentGENERAL REQUIREMENTS

• Ledger boards shall be attached to the existing house in accordance with the requirements herein. Compliance is critical to ensure the safety and structural stability of your deck.

• Ledger board depth shall be greater than or equal to the depth of the deck joists, but not less than a 2x8. • The ledger board shall be attached in accordance with one of the conditions shown in FIGURES 20

through 22. • The existing band board shall be capable of supporting the deck. If this cannot be verified or existing

conditions differ from the details herein, then a free-standing deck or an engineered design is required. • The top of the ledger board and top of the deck joists shall be at the same elevation.

Wood I-joists. Many homes are constructed with wood I-joists, as shown in FIGURE 19. Rather than utilize a 2x band board, these systems are often constructed with a minimum 1-inch thick engineered wood product (EWP) band board capable of supporting a deck. If a minimum 1-inch EWP or 2x band board is not present, then a free-standing deck or an engineered design is required.

Flashing. Flashing shall be installed in accordance with the following

FIGURE 19: WOOD I-JOISTS

requirements. See Page 3 for flashing material specifications. • The exterior finish, i.e., house siding, must be removed prior to the installation of the ledger board. • Continuous flashing, as shown in FIGURE 20, is required at the ledger board when attached to wood-

framed construction.


exterior sheathing

joist hanger

remove siding at ledgerprior to installation

12" diameter lag screws or

through-bolts or 14"approved wood screws

deck joist

2x ledger boardfoundation wall

existing 2x or 1" minimumEWP band board

existing stud wall

floor joist

continuous flashing

FIGURE 20: LEDGER BOARD-TO-BAND BOARD ATTACHMENT

12" diameter expansion

anchors with washers

deck joist

joist hanger

concrete or solidmasonry wall

2x ledger board

to resist corrosion and decay,this area should be caulked

embedment distanceper manufacturer

edge distance permanufacturer

FIGURE 21: LEDGER BOARD-TO-SOLID FOUNDATION ATTACHMENT

deck joist

8" block wall

12" diameter approved

adhesive anchors withwashers

joist hanger

hollow masonrywall

to resist corrosion and decay,this area should be caulked

2x ledger board attached to blockwall; attachment through brickveneer is prohibited

minimum

embedment distanceper manufacturer

edge distance permanufacturer

FIGURE 22: LEDGER BOARD-TO-HOLLOW FOUNDATION ATTACHMENT


Prohibited ledger attachments. The ledger board attachment conditions shown below are prohibited. In such cases, a free-standing deck or engineering design is required.

open webfloor trusses

deckjoist joist

deck

brick/stoneveneer ormasonrychimney

overhangor baywindow

FIGURE 23: PROHIBITED LEDGER ATTACHMENTS

LEDGER BOARD FASTENERS

General requirements. Ledger board fasteners shall be installed in accordance with this section. Placement and spacing shall be in accordance with FIGURE 24 and TABLE 6. Only those fastener types noted herein are approved for use; lead anchors are prohibited. Adequacy of connections will be verified by county inspectors.

typical spacing

interior fasteners;2 rows staggered

512" min. for 2x8

612" min. for 2x10

712" min. for 2x12

4 fasteners, eachend of ledger board

2"

2" min.

2"

34" min.

2" min.each end

FIGURE 24: LEDGER BOARD FASTENER SPACING AND CLEARANCES

TABLE 6: LEDGER BOARD FASTENER SPACING, INCHES ON CENTER

Fastener Band

Joist Span (feet), less than or equal to: Board 6 8 10 12 14 16 18

Lag Screws EWP1 24 18 14 12 10 9 8 2x lumber 30 23 18 15 13 11 10

Through-Bolts EWP1 24 18 14 12 10 9 8 2x lumber 36 36 34 29 24 21 19

SDS, LedgerLOK Wood Screws2 EWP1 12 9 7 6 5 4 4 2x lumber 13 10 8 6 5 5 4

SDWS Wood Screws2 EWP1 14 10 8 7 6 5 5 2x lumber 22 16 13 11 9 8 7

Expansion Anchors — 36 36 34 29 24 21 19 Adhesive Anchors — 32 32 32 24 24 16 16

1 EWP = 1-inch minimum manufactured engineered wood product; see Page 13 for more information. 2 Wood screws shall be permitted to be spaced in accordance with its current corresponding evaluation report if less restrictive than the values in TABLE 6.


Through-bolts. Through-bolts shall have a minimum ½-inch diameter. Pilot holes for through-bolts shall be 17/32 to 9/16 inches in diameter. Through-bolts must be equipped with washers at the bolt-head and nut. Bolts should be tightened six to 12 months after construction due to drying and wood shrinkage.

Expansion anchors. Expansion anchors shall be used only when attaching a ledger board to a concrete or solid masonry wall as shown in FIGURE 21. The bolt or threaded rod of expansion anchors shall have a ½-inch diameter minimum; in some cases, this may require a ⅝-inch anchor size. Expansion anchors must be installed per manufacturer’s instructions and shall be equipped with washers.

Adhesive anchors. The adhesive anchors listed in TABLE 7 with a minimum ½-inch diameter threaded rod shall be used when attaching to concrete or solid or hollow masonry as shown in FIGURE 22. Anchors shall be installed per manufacturer’s instructions and shall be equipped with washers. Adhesive cartridges must remain on the jobsite for inspector verification.

TABLE 7: APPROVED ADHESIVE ANCHORS Manufacturer Product

Red Head Epcon A7 Hilti HY-70

Lag screws. Lag screws shall be hot-dipped galvanized or stainless steel with a ½-inch minimum diameter. Length and shank requirements shall be in accordance with FIGURE 25. Lag screws shall be equipped with washers and installed in the sequence below.

1. Drill a ½-inch diameter hole in the ledger board and a 5/16-inch diameter pilot-hole into the solid connection material of the existing house.

2. Insert the lag screw through the ledger board and into the pilot hole by turning. Do not drive with a hammer. Use soap or a wood-compatible lubricant as required to facilitate tightening.

3. Tighten each lag screw snugly, but do not over tighten so as to cause wood damage.

existing band boardlength must extend through

(no threads)

1 2" d

ia.

112" shank

screw must penetrate beyondband board a minimum of 12"

FIGURE 25: LAG SCREW

Wood screws. The wood screws listed in TABLE 8 with a ¼-inch diameter may be used to attach to wood-framed construction. Wood screws shall have a sufficient length to fully penetrate the existing house band board. Installation shall be in conformance with the manufacturer’s instructions.

TABLE 8: APPROVED WOOD SCREWS Manufacturer Product

FastenMaster LedgerLOK Simpson Strong-Tie SDS Strong-Drive Screws Simpson Strong-Tie SDWS Strong-Drive Screws


7 Lateral SupportBRACING METHODS

All decks with post heights greater than 2.5 feet are required to be designed to resist lateral load caused by human activity and environmental forces. Use TABLE 9 to determine the applicable methods based on post height and deck type as defined in Section 3.

TABLE 9: LATERAL SUPPORT REQUIREMENTS Post Height (feet) less than or equal to: Single Span Decks Multi-span Decks Free-standing Decks

2.5 None required None required None required

11 • Method 1 or • Method 2

• Method 21 • Method 21 and • Method 3

14 • Method 1 and • Method 2

• Method 1 and • Method 2

• Method 1, • Method 2 and • Method 3

1 Method 2 may be omitted from the beam closest to the existing house wall if Method 1 is utilized at the house connection.

Method-1, Tension-ties (four total): • Install one tension-tie at each end joist and install the remaining two to inside joists equally spaced along

the width of the deck as shown in FIGURE 26. A set of tension-ties shall be installed for each structurally independent section of deck.

• Tension-ties shall be attached to the joists and exterior wall per the manufacturer’s instructions with specified fasteners as shown in FIGURE 27. Fasteners shall penetrate a minimum of 3 inches into the sill plate or top plate of a wood framed wall.

• Approved tension-ties are listed in TABLE 10. The minimum capacity of each tension-tie shall be 750 pounds.

• Where attaching to a concrete or solid masonry wall, fasteners are permitted to be substituted with expansion anchors or adhesive anchors with a threaded rod as recommended by the tension-tie manufacturer. The withdrawal capacity of the anchors shall be a minimum of 750 pounds. The anchor shall be installed per its manufacturer recommendations.

TABLE 10: APPROVED TENSION-TIES Manufacturer Product

Simpson Strong-Tie DTT1 USP LTS19 USP ADTT-TZ

install 4 tension-ties: one ateach end joist and two equally

spaced inside joists

FIGURE 26: METHOD 1 - TENSION TIE LOCATIONS


fastener permanufacturer

tension-tie

fastener permanufacturer

tension-tie

sill or topplate1

TO UNDERSIDE OF JOIST TO SIDE OF JOIST(DTT1 only)

2 rows, (10)10dnails or #10screws

TO ATTACHED BLOCKING(DTT1 only)

per tension-tie, but

not less than 24"

sill or topplate1

sill or topplate1

2x8 or 2x10blocking

max

imum

134"

for 2

x833

4" fo

r 2x1

0

1 Tension-ties may be anchored to concrete or solid masonry walls with expansion or adhesive anchors as permitted on Page 17.

FIGURE 27: METHOD 1 - TENSION-TIE CONNECTION

Method-2, Knee-bracing at beam: • Knee-bracing shall be comprised of 2x or 6x6 members. • Decks shall have 2x knee-bracing installed at each post-beam location or 6x6 knee-bracing at end posts

and both sides of every other interior post in accordance with FIGURE 28. • Connections of knee-bracing shall be in accordance with FIGURE 30 or 31.

2'

2'

2x KNEE-BRACING 6x6 KNEE-BRACING3'

-7"

3'-7"

beambeamjoists

2x knee-bracing 6x6 knee-

bracing

FIGURE 28: METHOD 2 - KNEE-BRACING AT BEAM-POST LOCATIONS

Method-3, Knee-bracing at joists-post locations (free-standing decks only): • Knee-bracing shall be comprised of 2x or 6x6 members. • Knee-bracing shall be installed at each post-joist location in accordance with FIGURE 29. • Connections of knee-bracing shall be in accordance with FIGURE 30 or 31.

2'

2x BRACING 6x6 BRACING

45°

3'-7

" 45°

blocking atunalignedjoists

joists

2x knee-bracing

6x6 knee-bracing

beam beam

FIGURE 29: METHOD 3 - KNEE-BRACING AT JOIST-POST LOCATIONS


BRACING-TO-FRAMING CONNECTIONS

AT JOIST OR BEAM

alternate bracingfrom front to backof posts

(2)20d nails or (2) approved woodscrews1 at all connections2

joist or beam

AT UNALIGNED JOIST

bracing, on frontor rear of post

AT POST

add blocking toaccommodateconnection

2 rows (10)10d nails or#10 screws2

24" min.

ORjoist or beam

1 Approved wood screws are listed in TABLE 8. 2 Nails shall have a distance of ⅜ inches to all edges and ⅞ inches to ends of the bracing member.

FIGURE 30: TYPICAL CONNECTIONS OF 2x KNEE-BRACING

AT POST AT BEAM OR JOIST

joist or beam

bracing

(1)12" lag screw, (2)20dnails or (2) approvedwood screws1

notch bracing and/orprovide blocking toaccommodate connection

34" min.

each side

12" horizontal

through-bolt

mitre/notchrecess in bracingfor fastener(s)

optional recess

post

bracing

1 Approved wood screws are listed in TABLE 8.

FIGURE 31: TYPICAL CONNECTIONS OF 6x6 KNEE-BRACING

8 Guards GUARD CONSTRUCTION

A guard is required when a deck is greater than 30 inches above grade at a point 36 inches from the edge of the deck, as shown in FIGURE 32. Guards shall be constructed in accordance with the requirements herein; deviations are prohibited. Guards which are not required, but are nevertheless provided, must also comply with these requirements.

Plastic composites. Plastic composites of equal dimension and complying with the criteria noted on Page 3 may be substituted for the guard cap and infill elements shown in FIGURE 33 provided the manufacturer’s performance criteria specifically permit such use.

Guard systems. Guard systems with a valid evaluation report from an accredited listing agency are permitted as referenced on Page 3. Pre-fabricated systems without an evaluation report will require a plan review during the permit application process.

36"

>30"

grade elevation point

edge ofdeck

deck

floo

rel

evat

ion

FIGURE 32: WHEN A GUARD IS REQUIRED

Openings. Guards shall be constructed to restrict the passage of a 4-inch diameter sphere through any opening. Wet lumber shall be spaced such that when shrinkage occurs, a compliant opening is maintained.


2x4 guard runnersfastened to guard postwith (2)8d nails or(2)#8 wood screws

(2)12" diameter throughbolts and washers

4x4 posts

6' maximumguard cap: 2x6, "five-quarter" board

attach balusters to guardrunners with (1)#8 woodscrew or (2)8d nails

2x2 balusters spacedsuch that a 4" diametersphere cannot pass

21 2"- 5

"

2" min. top & bottom

36" m

inim

um

attach guard cap to postwith (3)16d nails or(3)#12 wood screws

2x8 minimum FIGURE 33: GUARD CONSTRUCTION

GUARD POST CONNECTION

Guard posts shall be attached to the deck structure in accordance with the requirements below in order to ensure resistance to imposed loads.

• Notching guard posts, as shown in FIGURE 34, is prohibited. • Hold-down anchors, as shown in FIGURE 35 and FIGURE 36, shall be used to attach the guard post to

the end joist and rim joist, respectively. • Hold-down anchors shall have a minimum capacity of 1,800 pounds. • Guards may be attached to either side of the rim joist or end joist.

do notnotch

FIGURE 34: POST NOTCHES

PROHIBITED

PLAN VIEWSECTIONend joist

end joist

at first interior bay, provide full-depth 2xblocking at guard posts; toe nail with 10dnails top and bottom, each side

blocking

hold-down anchors

guardpost1 fasteners and

attachment perhold-downmanufacturer

guard post1

1 Guards can be attached to either side of the end joist.

FIGURE 35: GUARD POST-TO-END JOIST


between joistsat joist location

post alignedat joist1

hold-down anchor,fasteners permanufacturer

joist

rim joist

rim joist

SECTION PLAN VIEWS

rim joist

joist

joists

guard post1

guard post1

1 Guards can be attached to either side of the rim joist.

FIGURE 36: GUARD POST-TO-RIM JOIST

9 StairsSTAIR GEOMETRY

Stairs shall be constructed with the dimensions listed below.

• The minimum width of a stairway is 36 inches. • Stair geometry and opening limitations shall meet the

requirements shown in FIGURE 37. Treads, risers and nosing dimensions shall not deviate at each step by more than ⅜ inches.

STAIR LANDING

• If the total vertical height of a stairway exceeds 12 feet,

814"

max.riser

34" - 11

4"nosing

4" diametersphere shallnot pass

tread9" min.

tread

riser

FIGURE 37: TREADS AND RISERS

then an intermediate landing is required and must be constructed as a free-standing deck. • Stair landings may be constructed with 4x4 posts with post heights no greater than 8 feet. • Landing widths shall be equal to the total width(s) of the stairway(s) served.

STAIR CONSTRUCTION

Stair stringers: • Stringers shall be sawn or solid 2x12s complying with the tread and riser geometry requirements. • Stringers shall be spaced at a maximum of 18 inches on center. • Stringers shall bear on footings and attach to the deck or landing per FIGURE 38. • Stringer span length is measured using the horizontally projected distance between the bearing at each

end and shall not exceed the dimensions shown in FIGURE 39. SOLID STRINGER EXCEPTION: Solid stringers of stairways with a width equal to 36 inches shall be permitted to have a span as shown in FIGURE 39.

• Throat size of cut stringers shall not exceed the value shown in FIGURE 39.


landingstructure

sloped joisthanger

deck orlandingstructure

3" m

in.

beam or outside joist

beam or outside joist

LOWER BEARING AT LANDING UPPER BEARING AT DECK OR LANDING LOWER BEARING AT FOOTING

8" square or 10"round by 12" deepfooting

per hangermanufacturer

3" m

in.

toe nail with(3)8d nails

FIGURE 38: STRINGER BEARING

STRINGER SPAN

6'-9" maximum 13'-3" maximum

SOLID STRINGER EXCEPTION

514" minimum

throat

centerline of bearing

FIGURE 39: MAXIMUM STRINGER SPAN LENGTH

Tread and riser material: • Tread material shall be equivalent to the decking specified on Page 4 and attached in accordance with

FIGURE 40. The span of plastic composites shall be per manufacturer and in some cases may be less than 18 inches specified in FIGURE 40.

• Stairs constructed using the solid stringer exception shall have treads constructed of 2x wood material only; see FIGURE 40.

• Risers may be framed with 1x lumber minimum or equivalent plastic composite. Open risers are permitted provided the opening does not allow the passage of a 4-inch diameter sphere.

SOLID STRINGER EXCEPTIONCUT STRINGERS

2x ledger strip1, each side, fulldepth of tread; attach with(4)10d nails or (4)#10 screws

18" max. 18" max.

width = 36"typical tread attachment: (2)#8screws or (2)8d nails per boardat each stringer or ledger strip

2x woodmaterialonly

SAWN & CUT STRINGER COMBINATION

18" max. 18" max.

cutstringer

outside solidstringers

1 A galvanized staircase clip angle, installed per manufacturer’s instructions, is permitted to substitute for the 2x ledger strip.

FIGURE 40: STRINGER TREADS

Stair guards. Stair guards are required when the total rise of the stair is greater than 30 inches at a point 36 inches from the edge of the stair. Stair guards shall be constructed in accordance with Section 8 and FIGURE 41.


6' maximum

provide blocking between stairstringers and hold-down anchorsas shown at guard post locations;toe nail blocking with 10d nailseach side

guard post

triangular opening shall notpermit the passage of a 6"diameter sphere

34" - 38" (measuredfrom nosing of stepto top of stairguard)

FIGURE 41: STAIR GUARD

Handrails: • Stairs with four or more risers shall have a handrail on one side at a height between 34 to 38 inches

above the nosing of the step. • Handrails shall be attached to a stair guard or exterior wall acting as a barrier as shown in see FIGURE

42. • Handrail and connecting hardware material shall be decay and corrosion resistant. • Handrails shall have a smooth surface with no sharp corners and shall be graspable. Recessed sections

may be shaped from a 2x6 or five-quarter board as shown in FIGURE 43. • Handrails shall run continuously from a point directly over the lowest riser to a point directly over the

highest riser and shall return to the guard or wall at each end. • Handrails may be interrupted by guard posts at a turn in the stair only. • Handrails installed in lieu of window safety glazing, as required on Page 5, shall be supported at

appropriate intervals to ensure that when a 50-pound load is applied, the rail does not deflect into the glass.

34"-38" tonosing ofstairs

134" min.

2x blocking

112" min.

corrosion-resistanthandrail hardware

112" min.

guar

d po

stor

wal

l

guar

d po

stor

wal

l

attach blocking and handrailwith 8d nails @ 16" o.c.

guar

d po

stor

wal

l

handrail return attop and bottom

FIGURE 42: HANDRAILS

114" - 23

4"

34"

134"

min

.

114" - 2"

21 4" max.

RECESSED

78"

38"

516"

FIGURE 43: HANDRAIL GRASPABILITY


10 Complete My Deck

Prior to construction, design the specifics of your deck and complete the information required below. This information shall be available to the inspector at each inspection.

1. In the box below sketch your deck. Ensure beam and post locations and corresponding dimensions are shown. Show your deck’s overall length and width and any other necessary dimensions.

2. Complete the design details of your deck below.

DECKING: size: 2x4/2x6 five-quarter board direction: angled perpendicular material: preservative-treated lumber plastic composite non-native lumber PVC

JOIST 1: size: 2x6 2x8 2x10 2x12 spacing: 12 in. 16 in. 24 in. longest span: ____ft. - ____in. overhang: ____ft. - ____in. rim joist: 2x6 2x8 2x10 2x12 not applicable

JOIST 2: size: 2x6 2x8 2x10 2x12 spacing: 12 in. 16 in. 24 in. longest span: ____ft. - ____in. overhang: ____ft. - ____in. rim joist: 2x6 2x8 2x10 2x12 not applicable

BEAM 1: plies: 2 3 size: 2x6 2x8 2x10 2x12 influence width: ____ft. - ____in. longest span: ____ft. - ____in. overhang: ____ft. - ____in. footing size: ____in. square round thickness: ____in. post size: 4x4 6x6 post height: ____ ft. - ____in.

BEAM 2: plies: 2 3 size: 2x6 2x8 2x10 2x12 influence width: ____ft. - ____in. longest span: ____ft. - ____in. overhang: ____ft. - ____in. footing size: ____in. square round thickness: ____in. post size: 4x4 6x6 post height: ____ft. - ____in.

LEDGER BOARD: size: 2x8 2x10 2x12 not applicable (free-standing deck) fastener: through-bolt lag screw expansion anchor adhesive anchor wood screw spacing: ____in.

LATERAL SUPPORT (check all that apply): Method 1 Method 2 Method 3

fairfax county typical deck details county, virginia typical deck details based on the 2012 virginia...

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